Feeding mechanisms for sewing machines



Nov. 17, 1953 'KNAug 2,659,330

FEEDING MECHANISMS FOR SEWING MACHINES Filed June 30, 1950 2 Sheets-Sheet 1 Nov. 17, 1953 N. KNAUS 2,659,330

FEEDING MECHANISMS FOR SEWING MACHINES Filed June 50, 1950 2 Sheets-Sheet 2 .13? A/Mm (mam,

Patented Nov. 17, 1953 FEEDING MECHANISMS FOR SEWING MACHINES Nicholaus Knaus, Cranford, N. J., assignor to The Singer Manufacturing Company, Elizabeth,

N. J., a corporation of New Jersey Application June 30, 1950, Serial No. 171,325 6 Claims. (01. 112-209) This invention relates to feeding mechanisms for sewing machines, and more particularly to that type of feeding mechanism known as a differential feed in which two work feeding elements are adapted to be actuated so as to exert unequal feeding actions on the work, thereby either to stretch or full the work as required.

The invention has as a primary object to provide an improved differential feeding mechanism for sewing machines in which one of the two feeding elements may be dropped below the upper surface of the throat-plate when it is desired to discontinue the difierential feeding action.

With the above and other objects in view, as

will hereinafter appear, the invention comprises the devices, combinations and arrangements of parts hereinafter set forth and illustrated in the accompanying drawings of a preferred embodiment of the invention from which the several features of the invention and the advantages attained thereby will be readily understood by those skilled in the art.

Fig. i represents an end elevation, partly in section, showing the feeding mechanism assembled in a partially illustrated overseaining machine.

Fig. 2 represents a sectional view taken substantially along the line 2-2 of Fig. 1.

Fig. 3 represents a sectional view taken substantially along the line 3-3 of Fig. 1.

Fig. 4 representsa fragmentary elevation view illustrating with solid lines the auxiliary feed-bar in its operative position and illustrating with dotted lines such feed-bar in its inoperative or throw-out position.

Fig. 5 represents a sectional tially along the line 5-5 of Fig. l.

Fig. 6 represents a' disassembled perspective view of the main and auxiliary feed-dogs and their actuating connection rods.

Fig. 7 represents a perspective view of the main.

and auxiliary feed-dogs both in their operative positions.

Referring now to the drawings, the reference numeral iii denotes the frame or casing of an overseaming machine, ii the head and I2 the needle plate (see Fig. ll which is supported upon the frame in a conventional manner. The presser-foot I3 is supported on the head and the shank M of the foot is engaged by a compression spring :5 whereby the foot is normally pressed downwardly to confine the goods between the foot and the needle-plate l2. The rear portion of the shank i4 is mounted on a universal joint IS in a conventional manner and a lever I1 is provided for relieving the pressure of the view taken substano spring l5. The machine is provided with a main rotary shaft It (see Fig. 2) which is journaled in the frame Ill and this shaft, through a link not herein illustrated, is connected with a needle carrier l9 pivoted in a bushing 20 so that the rotation of the shaft I8 effects the oscillation of the carrier within its bushing The needle 2! is mounted in the carrier l9 and the oscillation of the latter causes the needle to reciprocate and penetrate the goods that is supported upon the needle-plate l2. Suitable stitch-forming implements or loopers cooperate with the needle to effect the formation of the overseaniing stitches, but as these lc-cpers and the manner of the means for their actuation form no part of the present invention, their illustration and further description are not deemed necessary.

For a more complete description and illustration of a machine of the present type, reference may be had to my United States Patent No. 2,338,796, dated April 15, 1941.

The present work-feeding mechanism is of the differential type including a main feed-dog and an auxiliary feed-dog which are mounted, respectively, on the side-by-side main and auxiliary fced-bars 2d and 25 slidably supported at their forked rear ends 26 and 2'! upon slide blocks 2t 29. The feed-bars and 25 receive their rising and falling movements from the feed-lift eccentric til on the main shaft it; said eccentric being surrounded the usual bearing block 3| which fits in ways 32 and 33 in the feed-bars 2d and 25. The feed and return movements are imparted to the feed-bars and 25 from main and auxiliary feed eccentrics and 35 remcvably and replaceably keyed upon the outer end of the main shaft l6 and held thereon. by the nut 35. The main feed eccentric 34 is connected by a pitman 3? to the lateral post 38 rigid with the main feed-bar 2-5. The aux iliary feed eccentric 35 is connected by a pitrnan 39 to a lateral post is rigid with the auxiliary feed-bar 25. Alteration of the amplitude of the feed and return movements of the feed-dogs is effected by substitution of feed eccentrics of the desired eccentricities, for those of the machine. In other words, to change the length of the horizontal feed movements of either or both of the feed bars 2 and '25 it is necessary to remove'one or both of the feed eccentrics 36 and as the case may be, and substitute another or others of greater or less eccentricity. It is therefore necessary that each machine shall be supplied with a suitable set, of eccentrics to produce the required different lengths of feed and degrees of gather- By means of the mechanism shown for giving the feed-dogs their four motion movements, it will be seen that each feeddog 22 and 23 may be caused to operate independently of its companion.

The differential feed mechanism of the present machine differs from that disclosed in my above noted U. S. patent in that the forked rear end 21 of the auxiliary feed-bar 25, which carries the forward feed-dog 23, embraces a slide block 23 which is mounted upon an eccentric stud 4| carried by a horizontally disposed rock shaft 42 journaled in a bearing bracket 43 formed at the rear end of the machine frame. The rock shaft 42 is spring biased to a position in which the eccentric stud 4| is lowered (see Figs. 4 and 5), thereby depressing the rear end of the auxiliary feed-bar and swinging the bar about the feed lift eccentric 30. This raises the forward end of the bar and the auxiliary forward feed-dog 23 carried thereby so that the auxiliary feed-dog is level with the main feed-dog 22. In this position the forward feed-dog has a greater effective feed stroke than the main feeddog and causes fulling of the lower ply of the material.

An arm 44, secured to and projecting rearwardly from the rock shaft 42 is connected by a chain 45 to a suitable foot treadle, whereby the rock shaft 42 may be turned to cause the rear end of the auxiliary feed-bar 25 to be elevated and the forward end thereof to be lowered to drop the auxiliary feed-dog 23 below the upper surface of the throat-plate l2 sufficiently to render the auxiliary feed-dog ineffective, while still permitting it to be given its back and forth and up and down movements.

More specifically, the bearing bracket 43 is surrounded by a coil spring 46 one end 41 of which is biased against the frame member while its other end 48 is biased against the arm 44 so that the entire mechanism is normally thrown into its operative position as hereinabove described. Thus, whenever the chain 45 is moved downwardly, as by means of a foot treadle, the arm 44 turns its rock shaft 42 and thereby throws the eccentric 4| upwardly so as to drop the auxiliary or forward feed-dog 23 beneath the throatplate |2. The arm 44 is secured to its rock shaft 4.2 by means of a screw 49, and the upward movements of this arm are arrested by means of a depending finger 50 formed on the machine frame.

From the above, it is to be understood that the bearing block 3| forms a support having an axis common to both feed-bars 24 and 25, with reference to which axis the feed-dogs have pivotal and longitudinal movements. Furthermore, it is about this support axis that the auxiliary feed-bar 25 pivots whenever the operator depresses the chain 45 for the purpose of lowering the auxiliary feed-dog 23 to its inoperative position.

The main or primary feed-bar 24 is also forked as at 26 and this fork member embraces a slide block 28 which is mounted upon an eccentric stud 5| carried by a horizontally disposed rock shaft 52 which is journaled in a bearing 53 at the rear of the machine frame. Referring particularly to Fig. 5, it will be seen that the distal end of this rock shaft is provided with a screw slot 54. By inserting a screw driver into this slot 54 and turning the shaft 52 the elevation of the main feed-dog 2.2 may be adjusted to proper limits.

From the above it will be appreciated that the ing or stretching.

present invention provides a simple but effective means for throwing one of the two feed-dogs out of effective operation during the running of the machine. Thus, whenever it is desired to discontinue the normal differential feeding action, it is only necessary to pull downwardly upon the chain 45 to effect a dropping of the auxiliary feed-dog 23 so that the latter will be effectively inoperative during the remaining portion of the sewing operation. By the same token, as soon as the operator wishes to render the auxiliary feed-dog operative so as to again effect a differential feeding action, it is only necessary to release the chain 45, whereupon the spring 46 will throw the arm 44 upwardly to pivot the auxiliary feed-bar 25 back into its operative position.

Having thus set forth the nature of the invention, what I claim herein is:

1. A sewing machine feeding mechanism comprising, a main feed-bar, an auxiliary feed-bar, a feed-dog carried upon one end portion of each of said feed-bars, means disposed intermediate the ends of said feed-bars for imparting lateral and differential longitudinal movements to said feed-bars, which lateral and differential longitudinal feed-bar movements constitute the work-feeding motions. normally stationary first and second means for respectively supporting the other end portions of each of said main and auxiliary feed-bars, and manually controlled means for causing relative lateral movement between said nrst and second supporting means thereby to render one of said feed-do s inoperative.

2. In a sewing machine, two co-acting feeding mechanisms each including a feed-bar and a feed-dog carried by said feed-bar, the workengaging surfaces of the two feed-dogs substantially defining a single horizontal plane, a rotary shaft disposed crosswise of said feed-bars, means on said shaft for imparting horizontal and vertical movements to each of said feed-bars, which horizontal and vertical feed-bar movements constitute the work-feeding motions, first and second members each slidably engaging and supporting one end portion of a respective one of said feed-bars, and manually controlled means for shifting one of said members vertically relative to the other thereby to pivot its associated feed-bar about said shaft so as to shift the feeddog carried by the latter feed-bar out of said plane.

3. In a sewing machine having, two oo-acting feeding mechanisms each including a feed-bar and a feed-dog carried upon one end of such feed-bar, a support forming a horizontal axis common to both feed-bars with reference to which axis the feed-dogs have pivotal and longitudinal movements, a shaft. and means on said shaft whereby vertical and differential horizontal longitudinal movements are imparted to said feed-dogs through the medium of said feed-bars; the invention which consists in the provision of means whereby one of said feed-dogs may be rendered inoperative. said last mentioned means comprising a pair of members each slidably engaging and supporting the other end portion of a respective one of said feed-bars, spring means for normally maintaining said pair of members positioned relative to each other so that the work-engaging surfaces of said feed-dog will substantially define a, common horizontal plane, and manually controlled means for shifting one of said members vertically relative to the other 5 thereby to pivot one of said feed-bars about said axis so as to shift one of said feed-dogs out of said common horizontal plane.

4. In a sewing machine, a frame, two co-acting feeding mechanisms each including a feed-bar and a feed-dog carried upon one end of said feedbar, a rotary element disposed intermediate the ends of said feed-bars and forming a horizontal axis common to both feed-bars with reference to which axis the feed-dogs have vertical pivotal and horizontal longitudinal movements, means connected with said rotary element whereby vertical and differential horizontal longitudinal movements are imparted to said feed-dogs through the medium of said feed-bars, first and second normally stationary means carried by said frame for respectively supporting the other end portion of each of said two feedbars, and a manually controlled lever carried by said frame for causing vertical relative movement between said first and second means thereby to pivot one of said feed-dogs about said axis.

5. In a sewing machine, a frame, two co-acting feeding mechanisms each including a feed-bar and a, feed-dog carried upon one end of said feedbar, a rotary element disposed intermediate the ends of said feed-bars and forming a horizontal axis common to both feed-bars with reference to which axis the feed-dogs have vertical pivotal and horizontal longitudinal movements, means connected with said rotary element whereby vertical and differential horizontal longitudinal movements are imparted to said feed-dogs through the medium of said feed-bars, first and second normally stationary means including a rockable eccentric member carried by said frame for respectively supporting the other end portion of each of said two feed-bars, a manually controlled lever carried by said frame and connected ing the slotted ends of said 6 with said eccentric member for rocking the latter thereby to pivot one of said feed-dogs about said axis, and spring means engaging said frame and said lever for maintaining said lever in a predetermined position relative to said frame.

6. In a sewing machine, a frame, two co-acting feeding mechanisms each including a feed-bar and a feed-dog carried upon one end of said feedbar, the other end portion of each feed-bar being formed with a longitudinal slot, a rotary element disposed intermediate the ends of said feed-bars and forming a horizontal axis common to both feed-bars with reference to which axis the feeddogs have vertical pivotal and horizontal longitudinal movements, means connected with said rotary element whereby vertical and differential horizontal longitudinal movements are imparted to said feed-dogs through the medium of said feed-bars, first and second normally coaxially arranged and stationary pins each disposed in a respective one of said feed-bar slots for supportfeed-bars, a manually controlled lever carried by said frame and connected with one of said pins for vertically adjusting such pin relative to the other pin thereby to pivot one of said feed-dogs about said axis, and spring means engaging said frame and said lever for maintaining said pins in a normally coaxial relationship.

NICHO'LAUS KN AUS.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,071,818 Stedman Sept. 2, 1913 1,178,988 Berger Apr. 11, 1916 1,231,133 Corrall June 26, 1917 

